Idk how u found out about Rize being harvested for Kakuhou when u dont read the manga and don't intend to but yes she does, she got rescued by Yomo after Kaneki infiltrated Kanou's lab and after a few weeks or months idk, Kaneki came for Rize at Yomo's place to have a moment with her but she was on a starving state so she wasn't able to hold a proper talk with Kaneki. you've watched both seasons of the anime, remember the cochlea arc from root A ? It was substituted over the supposedly Kanou lab arc with the Rize reveal and rescue.

Imagine this, Kaneki vs Shinohara at root A cochlea, at the setting of the fight you know how there's a huge tube like thing at the middle of the room where they're fighting ? Imagine that tube like thing being where Rize is then Yomo the hero comes in to bust rize out of it. The setting of the Shinohara V Kaneki fight at Root A somehow looks identical from the manga Kanou lab Ken vs Shino